Lathe



1964 H. SCHUMACHER LATHE Filed March 6, 1963 FIG. 2

United States Patent LATHE Hermann Schnmacher, Faurndau, Goppingen, Wnrttemberg, Germany, assignor to Gebr. Boehringer G.m.b.H., Goppingen, Wurttemberg, Germany, a limited-liability company Filed Mar. 6, 1963, Ser. No. 263,237 Claims priority, application Germany, Mar. 8, 1962, B 66,264 2 Claims. (Cl. 8232) My invention relates to a lathe and, more particularly, to the frame thereof provided with prismatic guiding means for a longitudinal slide and with a rack disposed therebelow for imparting movement to said slide.

It was the conventional practice heretofore to provide the frame at its top with a flange projecting horizontally and forwardly beyond the front face of the frame, said flange on its top being provided with the prismatic guiding means and at its bottom carrying the rack. In this prior design the prismatic guiding means were either integral with the flange or were formed by a bar fixed to the flange by screws. If desired, this bar was hardened. This prior design has the disadvantage that, where the prismatic guiding means is formed by a separate bar, such bar must be provided with threads which is undesirable, where the bar consists of hardened steel. Where the prismatic guiding means in integral with the flange of the frame, the hardening operation may result in an undesirable distortion of the frame. An additional hardening operation is required for the rack because the teeth of the rack must be hardened to reduce wear.

It is the primary object of my invention to simplify the frame structure including the prismatic guiding means and the rack and to provide an improved frame structure in which both the prismatic guiding means and the rack can be readily hardened without subjecting the frame to any distortion.

With the afore-said objects in view, the invention consists in the novel combinations and arrangements of parts hereinafter described by reference to a preferred embodiment of the invention and illustrated in the annexed drawing wherein like parts are designated by the same reference characters throughout the several views. It is to be clearly understood, however, that my invention is in no way restricted to the details of such embodiment but is capable of numerous modifications within the scope of the appended claims.

In the drawing FIG. 1 is a diagrammatic elevation of a lathe to which my invention is applicable,

FIG. 2 is a partial vertical cross-section taken along the line II-II of FIG. 1, the tool carrying slide being omitted therein, and

FIG. 3 illustrates the upper right-hand part of FIG. 2 on an enlarged scale including part of the transmission mounted on the tool carrying slide.

The lathe comprises in the conventional manner a bed or frame F carrying a spindle housing S and a tail stock T and being provided at its top with horizonal prismatic guiding means P extending horizontally lengthwise of the bed F for the guidance of a main carriage on wh ch the tool support B and a depending transmissionhousmg D are mounted. The transmission in housing D is dnven by a splined shaft (not shown) and includes a horizontal 3,157,077 Patented Nov. 17, 1964 shaft extending transversely to the prismatic guiding means P and projecting rearwardly out of the housing D. Its projecting end carries a pinion, such as pinion 20 shown in FIG. 3. This pinion matches with rack teeth on the frame and thus serves the purpose to impart horizontal movement to the slide C.

For the purpose of my invention I have provided the front wall 10 of the frame F with an upwardly facing shoulder 12 extending parallel to the upper edge 11 of the frame. Moreover, I have mounted a bar 13 on shoulder 12, the upper portion 15 of bar 13 projecting above the top face 14 of the frame and being formed with inclined prismatic guiding faces 22 and 23 for slidably guiding the slide C. The lower portion of the bar 13 is formed as a rack provided with teeth 16 meshing with the gear 20. The bar 13 has a plurality of horizontal transverse holes 17 for the accommodation of threaded bolts 18 which threadingly engage horizontal threaded bores 19 of the frame for the purpose of rigidly connecting the bar 13 with the frame F. Hence, it will appear that the rack provided with the teeth 16 and with the prismatic guiding means 15, 22, 23 is formed by a single bar 13 detachably fixed to the front face of the frame. This offers the following advantages:

The threads of the bores 19 are provided within a portion of the frame which is not hardened. Therefore, the mounting of the bar 13 on the frame F is simple and inexpensive. The teeth 16 and the inclined faces 22 and 23 of the prismatic guiding means can be hardened in a single hardening operation. The length of the teeth 16 can be reduced to a minimum whereby the pinion 20 in mesh therewith and its shaft rotatably mounted in the wall 21 of the transmission housing D will be subjected to a minimum of bending stresses. These bending stresses would be higher if the teeth of pinion 20 were longer. Moreover, the distance of the teeth 16 of the rack 13 from the prismatic inclined guiding faces 22 and 23 will be a minimum which is highly desirable in order to reduce the torque produced by the frictional resistance exerted on slide C by friction with the prismatic faces 22, 23 and by the driving force produced by gear 20. This couple tends to tilt the slide C about a transverse horizontal axis and, therefore, its reduction to a minimum is highly desirable.

Since I have formed the prismatic guiding means 15, 22 and 23 and the rack teeth 16 on the same bar 13, no

threads need be cut into any portion of the frame requiring a hardening operation. As a result, the assembly will be simple and the number of elements has been reduced to a minimum. Moreover, the teeth of the rack and the prismatic faces 22 and 23 may be hardened in a single hardening operation. The width of the rack may be reduced and the frame itself will be kept free from any bending stresses. Owing to the provision of shoulder 12 the forces are transmitted from the rack 13 to the frame F in a simple and reliable manner.

It will be obvious to those skilled in the art to which the invention appertains that the same may be incorporated in several different constructions.

Thus, the faces 22, 23 may be given the shape indicated by dotted lines in FIG. 3.

The accompanying drawing, therefore, is submitted merely as showing the prefered exemplification of the invention.

What I claim is:

1. In a lathe, the combination comprising a bed having an upwardly facing plane horizontal shoulder, a hardened bar projecting laterally from one side of said bed and having a plane bottom surface seated on said shoulder and being formed with a prismatic guide portion having upwardly inclined, upwardly converging, longitudinally extending guide surfaces, a tool-carrying slide mounted to reciprocate directly on said guide portion, a longitudinally extending rack integral with said bar, a transmission supported bysaid slide and including a pinion in mesh with said rack for imparting reciprocation to said slide, upon rotation of said pinion, and means for detachably securing said bar to said bed.

2. The combination claimed in claim 1, wherein said guide portion is at the top of said bar, and said rack is formed on the lower face of said bar.

References Cited by the Examiner UNITED STATES PATENTS WILLIAM W. DYER, JR. Primary Examiner. 

1. IN A LATHE, THE COMBINATION COMPRISING A BED HAVING AN UPWARDLY FACING PLANE HORIZONTAL SHOULDER, A HARDENED BAR PROJECTING LATERALLY FROM ONE SIDE OF SAID BED AND HAVING A PLANE BOTTOM SURFACE SEATED ON SAID SHOULDER AND BEING FORMED WITH A PRISMATIC GUIDE PORTION HAVING UPWARDLY INCLINED, UPWARDLY CONVERGING, LONGITUDINALLY EXTENDING GUIDE SURFACES, A TOOL-CARRYING SLIDE MOUNTED TO RECIPROCATE DIRECTLY ON SAID GUIDE PORTION, A LONGITUDINALLY EXTENDING RACK INTEGRAL WITH SAID BAR, A TRANSMISSION SUPPORTED BY SAID SLIDE AND INCLUDING A PINION IN MESH WITH SAID RACK FOR IMPARTING RECIPROCATION TO SAID SLIDE 